The subject matter disclosed herein relates to integrated circuits. More particularly, the subject matter relates to devices used to measure manufacturing processes in forming integrated circuits.
As integrated circuit (IC) technologies have advanced, the size of these devices has correspondingly decreased. In particular, as devices are reduced in scale to comply with ever-smaller packaging, tighter constraints are applied to their dimensions and spacings.
Smaller ICs call for advanced manufacturing techniques. In the lithography arena, one advanced manufacturing technique is extreme ultraviolet lithography (EUV), which utilizes small wavelengths (e.g., less than approximately 13.5 nanometers in length) to form features. However, EUV suffers from shortfalls, such as pattern-dependent and focus-dependent image shifting due to non-telecentricity of mask illumination optics. These shifts can be significant, given the overlay controls required in advanced IC technology nodes, and accurately measuring these shifts can be difficult.